Control apparatus for engine starters



y 1, 1 J. H. BOLLES 2,602,143

. CONTROL APPARATUS FOR ENGINE STARTERS Filed June 4, 1945 Cdroar 35 Y HYDRAULIC 5:19 /47-ro.eA/4=Ys Patented July 1, 1952 CQNTRQL APPARATUS FQR ENGINE STARTERS Julius ii. Belles, Anderson, Ind, assigncr to Gen- I oral Motors Corporation, Detroit, Mich, a corporation of Delaware Application June 4, 1345, Serial No. 597,467

1 6 Claims.

This invention relates to control apparatus for engine starter systems, particularly to that type of semi-automatic engine starter system in which the starter drive pinion is moved into engagement with the driven gear of the engine and the main starter switch is closed by action of an electromagnet, the energization of which is regulated by a control circuit,,which circuit is controlled by the operation of certain manual and automatic switches.

In certain starter systems of this character heretofore designed, switches operated by fluid pressure, either by manifold vacuum or engine oil pressure, have been provided to hold the control circuit open during operation of the engine under its own power in order to prevent the closing of the starter switch and energization of the starting motor when the engine is self-operative. This arrangement is provided because in the event that the starting motor were caused to become operative, either accidentally or otherwise, during self-operation of the engine, the movement of the starter pinion into engagement with the engine gear driven thereby would cause damage to such parts since the engine gear is in motion when the engine is running. In earlier starter control systems of this nature, the fluid pressure operated switch has been designed to be held closed during operation of the engine by the starting motor until the engine starts to operate under its own power.

Difficulty has been encountered in control systems employing a switch operated by vacuum, because when the engine is operating under its own power and with a heavy load at very low speed, the manifold vacuum drops until it is very low and approaches and may overlap, under certain conditions, the vacuum which is maintained when the engine is being operated by the starting motor before such engine becomes self-operative. The same difficulty is encountered to a lesser degree with an oil pressure operated switch because at low speed and under heavy load the oil pressure also approaches the oil pressure maintained while the engine is being operated by the starting motor.

Therefore, in earlier devices, whether the manifold vacuum or oil pressure is employed as :the operating medium for the switch, the latter has been so constructed that a very small force will hold it open. In fact, in order to insure that the fluid pressure operated switch would be open at all times that the engine was operating under its own power, it was necessary to provide a switch that would be held open by a force so low 2 that such switch might open under certain conditions during operation of the engine by the starting motor before the engine became selfoperative. In other words, the difference between the fluid pressure effective on the switch during cranking and under certain conditions when the engine was operating under its own powenbecarne so nearly the same that the switch could not be entirely successfully controlled. Either the switch would at times close during self-operation, or would open during cranking resulting in damage to the parts, or failure in starting of the engine. The principal purpose of the present invention is to eliminate this difliculty.

It is, therefore, the primary object of the present invention to provide a starter system of the type referred to in which the starter switch cannot under any circumstances be closed while the engine is operating under its own power and in which means are provided to prevent any possible opening of the starter switch during the cranking of the engine by the starting motor for the purpose of starting such engine.

The importance of providing a device of this character should be apparent and it is particularly important in devices where two engines are employed, and in large installations where the engine is at the rear or is otherwise so located that it is diiiicult for the driver to hear the engine. Where two engines are used, one may stop, but the driver of the vehicle does not know which engine is stopped, and may attempt to start the wrong engine. In case of a large vehicle with the engine located in the rear, the driver might not hear his engine, particularly in traffic, and attempt to start his engine while it is still running. Unless a device of this character were employed, disastrous results might follow.

With the above object in View, onefeature oi the present invention resides in the provision of a control circuit having a fluid pressure operated control switch for controlling the operation of the main starter switch, which will be effective when the engine is running under its 'own power to prevent closing of the main switch, but which is so arranged that the fluid pressure controlled switch will always be opened during the operation of the engine by the starting motor, that is, during the cranking of the engine, for the purpose oi starting, but without causing the opening of the main switch, whereby even if the fluid pressure switch is opened, the starting motor will not be caused to become inoperative.

A further feature of the invention consists in the provision of a fluid pressure operated switch which is preferably operated by oil under relatively heavy pressure such as the oil in any form of an hydraulic transmission as, for example, the fluid drive which is used in certain automotive vehicles now in wide use, and in the provision of a bypass circuit which is arranged to bypass the fluid pressure switch. The bypass circuit is closed when the manually operated switch of the control system is closed so that the oil under relatively high pressure will immediately open the fluid pressure switch, but the closing of the bypass circuit will prevent the opening of the main switch.

A further feature of the invention consists in the provision of means to prevent any subsequent closing of the control circuit after the fluid pressure switch is opened, in the event of accidental stalling of the engine until the fluid pressure switch has been permitted to close and to delay closing of the fluid pressure switch for a sufiicient period of time to insure that all moving parts of the engine come to rest before the starter switch can be closed. Where oil under relatively high pressure is used as the medium for operating the fluid pressure switch, this delay in closing of such switch is effected particularly eificiently, and there is always sufficient time for the moving parts of the engine to substantially come to rest before the starter circuit can be closed. In other words, the moving engine is effective until it has substantially stopped to maintain a sufficient degree of oil pressure, where the oil of the hydraulic transmission is used as a source of pressure, to maintain the switch in open condition until the engine has completely ceased tooperate. This time lag in the closing of the fluid pressure switch is most important in that it prevents any possible reclosing of the control circuit in the event of continual stalling until the parts are completely stationary and thus prevents any possible damage to the parts upon restarting after accidental stalling has taken place.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

The drawing is a diagrammatic view of a control mechanism for engine starters constructed in accordance with the present invention.

Referring to the drawing, the reference numeral indicates the starting motor which has a ground connection 22 and an armature shaft 24 on which is splined a slidable sleeve 26, which is secured to one member of an overrunning clutch 28, the other member of which is integral with a driving pinion 30, adapted to be moved into engagement with the flywheel gear 32 of the engine, in order to rotate said gear and start the engine whenever the starting motor is operative. The sleeve 26 is moved to the left, as the device is shown in the drawing, to effect engagement of the pinion 30 with the gear 32 and the circuit between the starting motor and the battery is concurrently closed to cause the starting motor to become operative.

To this end the sleeve 26 is provided with a grooved collar 34, which is slidable on the sleeve 26 and said collar is engaged by pins 36 which project from a yoke formed at the lower end of a lever 38, suitably pivoted at 40 and connected at its upper end with the armature 42 of an electromagnet indicated generally by the reference number 44, and which will be more specifically described later. The lever is connected to armature 42 by a pin and slot connection, the purpose of which will be described hereinafter, and which comprises the slot 46 in the upper end of the lever and the pin 48 on a link 56 connected to the armature and which projects into said slot.

When the electromagnet is energized the armature moves to the right, the lever moves collar 34 to the left, the collar pushing against a spring 52 which surrounds the sleeve 26 between the collar and the overrunning clutch previously referred to. The collar is positioned between one end of the spring and a plate 54 secured to the right end of sleeve 26. This movement of the lever pushes the whole sleeve and clutch assembly to the left and if the teeth of the pinion do not abut those of the flywheel, the pinion will be moved immediately into engagement with the flywheel gear. If there is tooth abutment between the pinion and flywheel gear, the spring 52 will be compressed as the lower end of lever 38 moves to the left until the starting motor switch is closed by movement of the armature 42, as more specifically described later. As the switch is closed, the first movement of the motor will move the pinion so that its teeth properly mesh with those of the gear 32, the spring 52 will expand and force the pinion into proper meshing engagement with said gear. This driving mechanism is the same as ordinarily used in manually operated starters of this type, the only change being the substitution of the magnetically operated lever 38 for the usual manually operated foot pedal. A spring 54 returns the lever 38 and associated parts to normal position when the magnet is de-energized.

The starting motor 20 is connected by the wire 56 with a fixed contact 58 of a starting motor switch, while a second fixed contact 66 is connected by a wire 62 with a battery indicated at 64 grounded at 66. A movable contact 16 is moved into engagement with the two fixed contacts to complete the starting motor circuit when the magnet 44 is energized, such movable contact being supported by a rod 12 which slides in a central aperture in the magnet core 14, and the left end of the rod extends beyond the core to the left so as to be engaged by the armature 42 as it moves to the right upon energization of the magnet. The armature pushes the rod to the right and moves contact 10 into engagement with contacts 58 and 60.

The movable contact 16 is mounted on a block of insulating material 16 which is mounted on the rod 12 between two flanges 18 and 86, which extend from the rod and a spring 82 surrounds the rod between the flange and the insulating material 16, such spring tending to hold the block of insulating material against the flange 18, as shown in the drawing. The rod 12 is normally held in the position shown in the drawing with the shoulder 80 bearing against the armature core by the action of a spring 84 which bears against the flange l8 and at the other end against a stationary part which is part of a bracket secured to the magnet housing and has a projection 86 fitting telescopically within a recess or central bore 88 in the rod 12. When the magnet is energized, the movement of the armature moves the rod 72 as previously described, and through the action of the spring 82, yieldingly presses the contact 10 into engagement with the fixed contacts. Upon deenergization of the magnet, the spring 84 restores the movable contact to the position shown in the drawing. I

When the starter switch has beenclosed in the manner indicated to complete the starting motor circuit, such motor rotates and the meshing of pinion 3i! and gear 32 having been accomplished in the manner described, the motor turns the gear 32 and starts the engine. When the latter is started and is running under its own power, the magnet will be de-energized and the spring 54 returns the parts to the position shown in the drawing, opening the starter switch and disengaging the pinion 30 from the gear 32.

The magnet 44 is provided with two windings 90 and 52, the winding 80 having a ground connection M, and the winding 32 being connected by a wire 06 with wire 56 which leads from the main starter switch to the starting motor so that the winding 92 is grounded through the starting motor.

The two coils of the magnet are connected by wires 98 and I00 with a wire I02 which leads to a fixed contact I04 of a magnetic switch or re lay B having a movable contact I06 which engages the fixed contact when the relay is ener gized, and is connected by a wire I08 with the battery. Whenever the contacts I04 and I06 are in engagement, current fiows from the grounded battery through wire I08, contacts I04 and I06, wire I02 and wires 93 and I00 to the magnet windings and thence to ground. The magnet is thus energized, resulting in operation of its armature to shift the pinion 30 and close the starter switch, both coils of the magnet being effective until the starter switch is closed. Just as soon as this takes place, the coil 92 is shunted out, so that the switch is held closed during the cranking of the engine only by the effect of the coil 90. This arrangement of the magnet with two coils, one of which is shunted out as soon as the main starter circuit is completed is substantially the same as disclosed in the patent to Dyer No. 2,302,687, November 24, 1942.

The operation of contacts I04 and I06 to effeet the energization and de-energization of the magnet 44 is efiected by a relay B which is controlled by a manually operable switch, a second relay A and a fluid pressure operated switch. The relay B which operates contact I06 comprises a core IIEI and a winding II2 which, at one end is connected by wire I I3 to a fixed contact II4 of a manually operable switch which includes a second fixed contact IIo connected by a wire I Hi to the wire 52 which leads to the battery, and a movable contact I20, normally held open by spring I22, but operable manually to bridge the contacts H4 and H6. The other end of the winding II2 is connected by wire I24 to a movable contact I26, which is normally open, but is movable by a relay, to be described later, into engagement with another fixed contact I28, grounded at I30. Whenever the manually cperable switch is closed and contacts I26 and I28 are closed, current flows through the winding I I2 and causes the magnet 44 to be energized. The operation of the contact I26 is so controlled that when the engine is not operating and the main ual switch is closed, the contact I26 will be immediately moved into engagement with the contact 28 and it will remain in engagement with the latter as long as the engine is being cranked by the starting motor and the manual switch is held closed, regardless of the effect of the fluid pressure control switch, but if the engine is op-- erating under its own power, it will be impossi- '6 ble to cause engagement of the contacts I26 and I23 upon closing of the manual switch.

To this end the contact I25 is operated by a relay A comprising core I32, and winding I34, which at one end is connected by a wire I36 to the wire II3 which leads to the manual switch. The other end of the winding I34 is connected by a wire I38 to an angular supporting member I40,

which carries a fixed contact I42 and is supported on a depending U-shaped bracket I44.

The supporting member I40 is held in fixed position on the bracket by the screw I46 and separated from the bracket by blocks of insulating material M8.

The bracket I44 is secured by brazing, or in other desirable way, to a flange I50 which projects from a cylinder I52. The latter is provided, at its upper end, with a peripheral groove in which is secured the lower part I54 of a diaphragm chamber, the upper part of which is indicated at I56. Clamped between the elements I54 and I56 is a diaphragm I58, and the upper part I56 of the diaphragm chamber is bent over at the periphery, as indicated at Hit, to clamp between this bent over portion and the portion I56, the lower part I54 and the diaphragm, so as to form a fluid-tight joint. A threaded nipple I62 is secured as shown at the center of the upper half I56 of the diaphragm housing and a conduit I64 is screwed into the nipple, as indicated in the drawing.

The conduit I54 may connect with the engine lubricating system at any suitable point to subject the diaphragm I50 to engine oil pressure or the conduit could connect with the intake mani fold to subject the diaphragm to engine suction,

in which case, the conduit would connect below the diaphragm I58, or the arrangement of contacts and controlling spring would be reversed. Such devices are disclosed in applicants copending application S. N. 773,539, filed Sept. 12, 194'? and now allowed. In certain istallations, as in automotive vehicles employing any form of an hydraulic transmission, it is preferable to connect the conduit I64 with the housing of the hydraulic transmission in any suitable way, so as to communicate to the diaphragm the pressure of the oil in such hydraulic transmission. Such an arrangement is shown diagrammatically in the drawing. This oil ismaintained under a very much higher pressure than is the oil in the lubricating system of the engine and when such pressure is communicated to the diaphragm I53, it is effective immediately when the cranking oi the engine by the starting motor begins to separate the contacts I42 and I16 of the fluid pressure switch and is also effective to maintain those contacts separated as long as the engine parts are moving. I

This is true because the oil pressure in the hydraulic transmission is so high by comparison to that of the oil in the lubricating system that it is under sufficient pressure when the parts are moving so slowly as to barely be in motion at all to create a sufiicient force on the diaphragm I58 to hold the switch contacts open. By use of this oil under high pressure, the closing of the contacts I42 and I'IIS is prevented until the engine parts have substantially ceased to operate. It, therefore, the engine accidentally stalls, it would be impossible to close the manual switch 220 and cause the closing of the starting motor circuit until the engine parts have ceased to move because the closing of switch 220 will not effect closing of the main starter switch until contacts I42 and I16 are in engagement.

Therefore, when oil under high pressure, for example, the oil of an hydraulic transmission, is employed as the operating means for the diaphragm I58, there is absolutely no possibility of closing the main starter switch when the engine is operating under its own power. Under any and all conditions of operation which could possibly be encountered, the pressure of the oil of the-hydraulic transmission would'be suflicient to keep the contacts I42 and I16 separated. As indicated previously, this arrangement is particularly effective in the case of a vehicle having two engines, where one engine stops and the operator of the vehicle does not know which engine has ceased to operate, or in large installations when the engine is located at a relatively great distance from the driver of thevehicle. In the first instance, the driver would not know which of the engines was not in operation in case one of them stopped and in the case of a large installation, he might not hear the engine and think it had stopped when it was actually still in operation. In either case it would be entirely impossible for him to close the switch of the starting motor of an engine which is in operation. If he closes the manual switch which controls the starting motor of an engine in operation, nothing happens because the fluid pressure switch is necessarily open.

A rod I66 is connected in any suitable way to the center of the diaphragm and extends downwardly therefrom through the cylinder I52. At its lower end, the rod is reduced in size as indicated at I68 and surrounding this part of the rod is a washer I10 and a flanged collar I12 of insulating material. Received around the cylindrical part of the collar and between the washer I16 and the flange which projects from the collar is a spring I14, supporting a movable contact I16 which is adapted to engage the fixed contact I42 when the engine is not in operation. The reduced part I 68 of the rod I66 is riveted over the flanged collar, as shown in the drawing, to hold the collar in position. The cylinder I52 is closed at its lower end except for an orifice in which the rod I66 fits loosely, and a spring I18 is positioned in said cylinder around the rod, between the closed lower end of the cylinder and the diaphragm I58, such spring acting to hold the diaphragm in the position with the switch contacts I42 and I16 in engagement when the engine is inoperative. The spring is connected, as indicated in the drawing, by a wire I86 which extends from the spring to one of the brushes of the generator I82 which is grounded as indicated at I64. Therefore, the spring I18 is grounded through the generator and the connection I84. The generator is connected by the wire I86 to the battery to effect charging thereof and the usual cut-out relay I88 is provided in this connection. The generator and the connection therefrom to the battery is of conventional construction and need not be further described.

It will be understood that if the spring I18 is grounded through the generator, as described, the main magnet may be rendered inoperative by the generator when the latter reaches a predetermined speed and under certain operating conditions, for reasons which will be more fully set forth in the description of the operation of the device that appears hereinafter.

Attention is called to the fact that the spring I18 may have a ground connection leading direct- 1y from the spring to ground without passing through the generator. As will be apparent from the description of the operation which follows later on, if the device is constructed in this way, the starting motor will always continue to operate until the manually operable push button 220 is released, whereas if grounded through the generator, as illustrated in the drawing, the starting motor, under certain circumstances, may be rendered inoperative by the generator as soon as the engine begins to run under its own power and operates rapidly enough to bring the speed of the generator up to the point required to cause the de-energization of the main magnet. Likewise, if the generator ground connection is used as shown, the generator will prevent any possibility of accidental operation of the starting motor during self-operation of the engine, even in the event of failure of the fluid pressure switch.

For a purpose to be more fully explained, there is a second ground connection for the wire I38, when the contacts I26 and I 28 are closed. To

this end a wire I96 is connected to the wire I38 and is also connected to the switch contact I26.

It will be understood that instead of connecting the upper half of the diaphragm with a source of oil under pressure to effect opening of the contacts I42 and I16, when the engine is in operation, the upper part of the diaphragm chamber could be made solid except for a vent and a suction conduit could be connected to the lower part of the diaphragm chamber and the intake manifold so as to communicate the engine suction to the lower side of the diaphragm to pull the diaphragm down'when the engine is running.

From the foregoing description, it will be apparent that the normal position of the parts, that is, the position of such parts when the engine is inoperative is as shown in the drawing, with the pressure operated switch closed. If the manually operated switch button 220 is then operated to close the switch operated thereby, current will first flow from the battery through such switch, the wire I53, wire I36, winding I34, wire I38, contacts I42, I16, spring I14 and connection I through the generator to ground. This will energize relay A and effect closing of contacts I26 and I28. Closing of these contacts will immediately cause the energization of relay B because current flows from the battery, through the manual switch, winding I42, wire I24 and contacts I26, I26 to ground. As soon as relay B is energized, the main magnet 44 is energized, the main starter circuit is closed and the pinion 38 is moved into mesh with the gear 32 as previously described. The engine will then be cranked and ultimately will be started.

During the cranking of the engine, fluid pressure, either the oil pressure or manifold vacuum, whichever is used, will be eifective to move the diaphragm down against the force of springs I14 and I18. Under some conditions, the force exerted by this fluid pressure is great enough, even during the cranking period and before the engine begins to operate under its own power, to cause separation of contacts I42 and I16, but with the device disclosed, this cannot cause the cle-energization of the main magnet 44, nor cause the starting motor to become inoperative, unless the operator, himself, opens the manually operated switch. Operation of the generator may cause the de-energization of the main magnet under certain circumstances, but never during cranking, as the generator speed is insufficient.

Because of the second ground connection for under its own power, neither the relay A nor the main magnet will be energized, even if the fluid pressure falls so low that the fluid pressure switch is closed, so that the starting motor cannot be caused to become operative. Even if the fluid pressure became so low that the switch operated thereby were closed, the generator would be operating rapidly enough to ie-energize the winding I34 and the closing of the manually operated switch would have noeffect. Y

Ordinarily the-generator has no effect in causing de-energization of the main magnet, but is effective in the event of failure of the fluid pressure switch or great delay'in the operation of such switch, to bring about the de-energization of the main magnet when the engine-operates under its own power and fast enough to drive the generator at more-than a predetermined speed,

If at any time when the generator is operat: ing at a. speed above thepredetermined speed referred to and the fluid pressure switch is closed, current will flow from the generator through wire its, the fluidpressure switch and wire I38 to the winding I34 through which it flows in a direction opposite to the current flowing from the battery. This nullifles the action of the bat tery current on said winding, and causes contacts 126 and I28 to separate, which results in the tie-energizing of the magnet for reasons that will be apparent. Whenever the fluid pressure switch is open, current from the generator cannot flow to the winding I34, so-that the generator has no de-energizing function at any time that said fluid pressure switch is open. Since the fluid pressure switch is opened under normal circumstances during engine cranking and before the generator is operated at sufficient speed to have any effect, the main magnet is de-energized, under normal conditions only by. openingof the manual switch l 7 However, if there should be any failure of the fluid pressure switch due to a broken diaphragm, or for any other reason, or if there is sufficient delay in the operation of the fluid pressure switch, due to oil viscosity or any other cause, which is sufficient to enable the generator to attain the necessary speed of operation before the opening of the fluid pressureswitch, the actionof the generator will de-energize the main magnet.

Likewise the generator will prevent any energization of the main magnet during self operation of the engine if themanual switch be accidentally closed. In the event of failure of the fluid pressure switch, or if the speed of the engine would be reduced sufliciently to enable the closing of the fluid pressure switch, operation of the manual switch would not cause the main magnet to be energized because as soon as the fluid pressure switch closed, the generator would de-energize winding 134 and closing of the manual switchwould not effect closing" of contacts I26 and I28.

Normally, when the engine starts to operate under its own power, the fluid pressure separates the contacts I 42 and H6 and the operator releases the manual switch. The opening of the fluid pressure switch breaks one ground connection of the relay A and the opening of the manual switch breaks the other ground connotation of such relay, comprising contacts E25 and I28.

Under normal conditions, the fluid pressure switch remains open as long as the engine is selfoperative-and accidental closing of the manual switch will have no effect. Under abnormal conditions such as previously referred to, the action of the generator will effect opening of the contacts 126 and 128, when the fluid pressure switch fails to remain open, whenever the engine is selfoperative, so that accidental operation of the manual switch cannot cause the main magnet to operate as long as the engine is self-operative, regardless of what may happen to the fluid pressure switch, or how long a delay there may be in the. action of the fluid pressure switch.

As already stated in the foregoing description, the fluid pressure switch which is operable by the engine may be operated by either oil pressure or by the engine suction or manifold vacuum. The oil pressure operated switch has one advantag which may be mentioned. Sometimes in starting an engine, the engine will make two or three rotations and then stop. Due to the inertia of the parts, they will remain in motion for a brief period of time and if the pressure operated switch could close during such period of time, it might result in the starting motor being rendered effective because the manually operated switch would be-still closed by the operator. This would result in damage to the starter pinion and flywheel gear so that it is desirable to prevent any possible reclosing of the pressure operated switch under such conditions. When oil pressure is employed there is a definite lag in the operation of the switch due'to the viscosity of the oil, particularly in cold weather. This delay will cover a period of several seconds and is sufficient to assure that the engine parts are fully stopped before the reclosing of the switch can take place.

'This application is a continuation-in-part of applicationSerial No. 542,475, filed June 28, 1944, now abandoned. V

QWhile the embodiment of the present invention as; herein disclosed, constitutes a preferred form, it-isto beunderstood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Engine starting apparatus for internal combustion engines comprising, in combination, a current source, a starting motor adapted to be operated by current from said source, a main switch for controlling the circuit between the current source and starting motor, a control circuit for controlling the'operation of the main switch which includes a control switch operated by oil from a source, of supply in which the oil is maintained under high pressure during self-operation of the engineunder all conditions, and also when the engine isbeing rotated by the starting motor andso constructed that the pressure created by the-engine, either when operated bythe starting motorfor when self-operative, always i effective to open the switch, and which must be closed to cause the initial closing of the main switch, a second switch in circuit with the fluid pressure switch and effective upon closing to bring about theclosing of the main switch, a third control switch, the closing of which is effected by the closing of said second mentioned switch and when closed is effective to maintain the main switch closed irrespective Of the oil pressure switch, whereby the latter may be opened after the closing of said third switch without causing the starting motor to become inoperative and a generator effective to prevent closing of said third switch when the engine is self-operative.

2. Starting apparatus for internal combustion engines comprising, in combination, a. current source, a starting motor operable by current from said source, a main starter switch adapted to close the circuit between said current source and the starting motor, a magnetic switch between the current source and the main switch operable to effect closing of the main switch when it is closed, a control circuit for the magnetic switch which includes a control switch operable by oil from a source of supply in which the oil is maintained under high pressure during self operation of the engine under all conditions and when said engine is being rotated by the starting motor and so constructed that said pressure operated switch always is opened by the pressure efiective thereon when the engine is self-operative and when said engine is being rotated by the starting motor, a second magnetic switch in circuit with the winding of the first magnetic switch whereby the second magnetic switch must be closed in order to efiect energization of the closing of the first magnetic switch, said second magnetic switch having a winding in series with the oil pressure operated switch and means for establishing a ground connection for said winding when the second magnetic switch is closed, whereby said winding will remain energized after the closing of the switch irrespective of the pressure operated switch.

3. Starting apparatus for internal combustion engines comprising, in combination, a current source, a starting motor operable by current from said source, a main starter switch adapted to close the circuit between said current source and the starting motor, a magnetic switch between the current source and the main switch operable to effect closing of the main switch when it is closed, a control circuit for the magnetic switch which includes a control switch operable by'oil from a source of supply in which the oil is maintained under high pressure during self operation of the engine under all conditions and when said engine is being rotated by the starting motor and so constructed that said pressure operated switch always is opened by the pressure effective thereon when the engine is self-operative and when said engine is being rotated by the starting motor, a second magnetic switch in circuit with the winding of the first magnetic switch whereby the second magnetic switch must be closed in order to effect energization of the closing of the first magnetic switch, said second magnetic switch having a winding in series with the oil pressure operated switch, means for establishing a ground connection for said winding when the second magnetic switch is closed, whereby said winding will remain energized after the closing of the switch irrespective of the pressure operated switch, a generator and a connection between the winding of said second magnetic switch and the generator whereby the generator causes de-energization of said second magnetic switch when the engine is operating under its own power.

4. Engine starting apparatus for internal combustion engines comprising, in combination, a current source, a starting motor adapted to be operated by current from said source, a main switch for controlling the circuit between the current source and starting motor, a control circuit for controlling the operation of the main switch which includes a control switch operated by oil'from a source of supply in which the oil is maintained under high pressure during self operation of the engine under all conditions and when said engine is being rotated by the starting motor so that said switch is always opened during rotation of the engine by the starting motor, a second control switch in said control circuit in series with the oil pressure switch and efiective upon closing to bring about the closing of the main switch, a third control switch in series with said second control switch and means operable to close said third control switch when said second control switch is closed, in order to establish a by-pass control circuit around the oil pressure operated switch which, when closed, maintains the main switch closed when the oil pressure switch is opened, whereby opening of the latter will not de-energize the starting motor.

5. Engine starting apparatus for internal combustion engines comprising, in combination, a current source, a starting motor adapted to be operated by current from said source, a main switch for controlling the circuit between the current source and starting motor, a control circuit for controlling the operation of the main switch which includes a control switch operated by oil from a source of supply in which the oil is maintained under high pressure during self operation of the engine under all conditions and when said engine is being rotated by the starting motor so that said switch is always opened during rotation of the engine by the starting motor, a second control switch in said control circuit in series with the oil pressure switch and effective upon closing to bring about the closing of the main switch, a third control switch in series with said second control switch, means operable to close said third control switch when said second control switch is closed in order to establish a by-pass control circuit around the oil pressure operated switch which, when closed, maintains the main switch closed when the oil pressure switch is opened whereby opening of the latter will not deenergize the starting motor, means by which the third control switch may be opened after the engine starts to operate on its own power and means for preventing the re-closing of said third control switch as long as the engine continues to operate.

6. Engine starting apparatus for internal combustion engines comprising, in combination, a current source, a starting motor adapted to be operated by current from said source, a main switch for controlling the circuit between the current source and starting motor, a control circuit for-controlling the operation of the main switch which includes a control switch operated by oil from a source of supply in which the oil is maintained under high pressure during self operation of the engine under all condition and when said engine is being rotated by the starting motor, and so constructed that the pressure created by the engine, either when operated by the starting motor or when self operative will always be efiective to open the switch, and which must be closed to cause the initial closing of the main switch, a second switch in circuit with the fluid pressure switch and effective upon closing to bring about the closing of the main switch, a third control switch, the closing of which is effected by the closing of said second mentioned switch and 13 which, when closed, is effective to maintain the main switch closed irrespective of the oil pressure switch, whereby the latter may be opened after JULIUS H. BOLLES.

REFERENCES CITED The following references are of record in the file of this patent:

Number 14 UNITED STATES PATENTS Name Date Warner May 9, 1933 Maurer May 16, 1933 Maurer Nov. 28, 1933 Sayre Nov. 27, 1934 Sayre Nov. 27, 1934 Maurer Oct. 8, 1935 Maurer 1- Apr. 27, 1937 Dyer et a1 Jan. 18, 1938 Elkin Oct. 31, 1939 Korte et a1. Oct. 22, 1940 White May 19, 1942 White Dec. 14, 1943 

